Field of the Invention
The invention relates to a process for the coating of components, wherein by means of a spray technique a plastic-containing layer is deposited onto the surface of the components.
The coating of components of metallic or nonmetallic materials is carried out in particular with a view to long-term corrosion protection, abrasion resistance, service life, etc. By means of plastic layers on components, for example, vessels or pipelines in the chemical industry, it is possible to save expensive materials such as stainless or acid-resistant steels. The components may consist of inexpensive load-bearing materials, while the chemical resistance, the corrosion protection, the abrasion resistance, etc. are achieved by means of the plastic layer. As a rule, the manufacture of heavy-duty plastic layers on a component is carried out by one of three important process techniques: fluidized-bed coating, electrostatic spraying and flame spraying. The fluidized-bed coating, the component, after sand blasting, is heated to the temperature required in each case in a heated furnace and thereafter lowered into the fluidized bed. Upon contact of the component--which has been preheated to the melting point of the plastic--with the powdered plastic, which is fluidized by means of compressed air, the plastic melts and forms a close-packed, smooth and pore-free layer. Mass-produced components with complex surfaces can thus be coated economically. The basic principle of the electrostatic spraying process lies in charging powdered plastic particles electrostatically during the spraying onto the surface of the component, thereby causing them to adhere upon impact and forming a uniform, loose layer. The layer sprayed on in this manner is then fused in an electrically heated furnace. In flame spraying, specially designed spray guns are used, which are usually operated with a combustible-gas-oxygen flame and compressed air. With spray guns one can spray synthetic-type plastics such as, polyesters, polyethylene, epoxides, etc., whereby the sprayed plastic layers so obtained have known technology-related physical as well as chemical properties, which need not be further discussed herein.
Furthermore, West German Pat. No. 3,033,579 discloses a backfire-immune coating device for the application of metallic coating material on metallic support surfaces to be coated. Such a coating device contains a spray gun by means of which, on the one hand, the metal powder and, on the other hand, two combustible-gas components, especially acetylene and oxygen, are supplied to the component.